1. Field of Invention
The field of art to which this invention relates includes, generally, the manufacture of "cards" or substrates on which are formed or mounted electrical circuits and, more particularly, includes a new and improved method and apparatus for forming a plurality of pins automatically on a substrate.
2. Description of the Prior Art
The method used today for mounting a plurality of pins on a substrate is embodied in an apparatus having three major functions: (1) multiple pin feeding into a plurality of holes preformed in each substrate, (2) substrate feeding into this machine and (3) the attaching (or fixing) of each pin within its hole to hold it in place (called a "heading" and "bulging" operation). These functions are performed, along with other less primary operations, on seven separate stations of an eight station rotary indexing machine.
The multiple pin feeding function involves a linear vibrator, pin feeding tube and a pin escapement mechanism. Several thousands of pins are dumped into a vibrating "hopper" (area). They are separated and vibrated down a "V" shaped slot into a tube. The tube, in turn, connects the vibrator to a pin escapement device where the pins are released and pushed, as a group, into an awaiting pin holder and positioner on the index table.
Next, the index table rotates to a substrate loading station where one substrate is positioned to receive the pins being held in the pin holder.
With each hole in the substrate (360 or more) being filled with a pin, the index table rotates, again, to a "heading" and a "bulging" station where the group of pins is cold formed for retention mechanically in the holes. Finally, the index table rotates to another station for ejecting the completed substrate.
While the eight station rotary indexing machine has performed effectively in the past, it has not been entirely without problems. Getting a great number of very small, preformed pins into hundreds of small holes automatically has been one of the problems, and the cold forming of each pin frequently results in loose pins.
As technology has advanced over the past years, the diameter of these preformed pins has become smaller and smaller, until today when the diameter is 0.020 inch, and the length approximates 0.25 inch. Smaller pin sizes make the feeding of thousands of preformed pins by vibrating into smaller holes in the substrate such a limitation that the efficiency of the eight station rotary indexing machine is affected dramatically.
Utilizing the present invention, the disadvantages of the prior eight station machine are avoided entirely. The number of working stations is reduced from eight to one, there are no loose preformed pins to feed into very small holes, the speed of operations is increased, cost is reduced and all pins are fixed firmly in place.